TY - JOUR
T1 - Spin-gap formation due to spin-Peierls instability in -orbital-ordered
AU - Miyajima, Mizuki
AU - Astuti, Fahmi
AU - Fukuda, Takahito
AU - Kodani, Masashi
AU - Iida, Shinsuke
AU - Asai, Shinichiro
AU - Matsuo, Akira
AU - Masuda, Takatsugu
AU - Kindo, Koichi
AU - Hasegawa, Takumi
AU - Kobayashi, Tatsuo C.
AU - Nakano, Takehito
AU - Watanabe, Isao
AU - Kambe, Takashi
N1 - Funding Information:
The authors acknowledge fruitful discussions with H. O. Jescheke, J. Otsuki, M. Naka, K. Okada, R. Kondo, T. Goto, H. Sagayama, and R. Kumai. The x-ray diffraction study was performed under the approval of the Photon Factory Program Advisory Committee (Proposals No. 2017G636, No. 2019T003, and No. 2020G666). The neutron scattering experiment at the HRC was approved by the Neutron Scattering Program Advisory Committee of IMSS, KEK (Proposal No. 2019S01), and ISSP. This work was partly supported by JSPS KAKENHI (Grants No. 15H03529, No. 20K20896, and No. 21H04441), MEXT, Japan.
Funding Information:
High Energy Accelerator Research Organization Photon Factory Program Advisory Committee Japan Society for the Promotion of Science Ministry of Education, Culture, Sports, Science and Technology
Publisher Copyright:
©2021 American Physical Society
PY - 2021/10/1
Y1 - 2021/10/1
N2 - We have investigated the low-temperature magnetism of sodium superoxide (), in which spin, orbital, and lattice degrees of freedom are closely entangled. The magnetic susceptibility shows anomalies at K and K, which correspond well to the structural phase transition temperatures, and a sudden decrease below K. At 4.2 K, the magnetization shows a clear stepwise anomaly around 30 T with a large hysteresis. In addition, the muon spin relaxation experiments indicate no magnetic phase transition down to K. The inelastic neutron scattering spectrum exhibits magnetic excitation with a finite energy gap. These results confirm that the ground state of is a spin-singlet state. To understand this ground state in , we performed Raman scattering experiments. All the Raman-active libration modes expected for the marcasite phase below are observed. Furthermore, we find that several new peaks appear below . This directly evidences the low crystal symmetry, namely, the presence of the phase transition at . We conclude that the singlet ground state of is due to the spin-Peierls instability.
AB - We have investigated the low-temperature magnetism of sodium superoxide (), in which spin, orbital, and lattice degrees of freedom are closely entangled. The magnetic susceptibility shows anomalies at K and K, which correspond well to the structural phase transition temperatures, and a sudden decrease below K. At 4.2 K, the magnetization shows a clear stepwise anomaly around 30 T with a large hysteresis. In addition, the muon spin relaxation experiments indicate no magnetic phase transition down to K. The inelastic neutron scattering spectrum exhibits magnetic excitation with a finite energy gap. These results confirm that the ground state of is a spin-singlet state. To understand this ground state in , we performed Raman scattering experiments. All the Raman-active libration modes expected for the marcasite phase below are observed. Furthermore, we find that several new peaks appear below . This directly evidences the low crystal symmetry, namely, the presence of the phase transition at . We conclude that the singlet ground state of is due to the spin-Peierls instability.
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U2 - 10.1103/PhysRevB.104.L140402
DO - 10.1103/PhysRevB.104.L140402
M3 - Article
AN - SCOPUS:85116791364
VL - 104
JO - Physical Review B
JF - Physical Review B
SN - 2469-9950
IS - 14
M1 - L140402
ER -